1. Field of the Invention
The present invention relates to magnetic data recording devices, and more particularly to thin-film micro electromechanical system (MEMS) electronic devices placed in magnetic stripes that provide for a dynamic part of an otherwise static data recording.
2. Description of Related Art
Magnetic data recordings have been an important medium for use in video, audio, and computer data storage. Tapes have been configured on reels, cassettes, and cartridges. Short segments of magnetic stripes on the backs of credit, payment, and identity cards are ubiquitous ways to make wallet cards machine readable and more secure. Such magnetic stripes on credit cards have enabled worldwide use in merchant point-of-sale (POS) terminals.
Jacob Wong describes a credit card (11) with a magnetic stripe (12) on the back, in U.S. Pat. No. 6,592,044, issued Jul. 15, 2003. Such patent is incorporated herein by reference. The card described by Wong is intended to be read by a standard POS card reader, and has the conventional three tracks of data (13-15) common to modern payment cards. A small encoder (16,25) is embedded in the magnetic stripe, e.g., a part of the middle track (15). The encoder provides for the generating of a data packet that “can contain a personal coupon and an alias.” Such personal coupon is produced by a collocated and embedded microprocessor (16) after a personal identification number (PIN) is input into the card. Wong explains that Track-1 was originally defined by the International Air Transport Association (IATA), and records seventy-nine alpha-numeric characters recorded at 210-bpi. Conventionally, it contains the cardholder's name, account, and discretionary data. Track-2 was originally defined by the American Banking Association (ABA), and this is the track that is read by ATMs and credit card readers. It records forty binary coded decimal (BCD) characters at 75-bpi. Wong's encoder is placed in one segment of this track and occupies less than all forty character positions. The ABA track specifications have been adopted by all the major banks in the world. Track-2 has data fields used to record the cardholder's account number, expiration date, possibly an encrypted PIN, and bank or card issuer discretionary data. Track-3 was used by ATM machines for withdrawal limits or history, and is still included for future definition and use, but it still as yet has not found any standardized widespread use. It provides for 107 BCD characters recorded at 210-bpi.
The problem that developed with conventional credit cards was that the data recorded on the magnetic stripe could be easily duplicated or “skimmed” off the card. The data collected was valid everywhere for every transaction until the victim detected and reported the theft. The better solution was to make each access number unique for each transaction, so that data from a skimmed card became instantly obsolete when the cardholder used it in a valid transaction. A card that does just this is described in U.S. patent application Ser. No. 11/404,660, filed Apr. 14, 2006, by the present inventor, Kerry Dennis BROWN, and titled AUTOMATED PAYMENT CARD FRAUD DETECTION AND LOCATION.
Implementing the electronics that can change all or parts of the magnetic recording on the magnetic stripe of a credit card is difficult and challenging. Everything must fit within a very thin flexible plastic card, and such must be compatible with all legacy card readers. Requiring special card readers will prevent all but limited acceptance. The generating and writing of the new magnetic data for the next transaction requires some kind of energy source, and flat thin batteries are the most practical. These batteries must provide a useful service life, e.g., at least two years in normal use. The per-card manufacturing costs also need to be low enough to make widespread deployment practical and affordable. Some of these costs might be absorbed by the savings gained by reducing skimming fraud, but in general the cards including these technologies need to be a few dollars per card in volume.
What is needed is a magnetic encoder or device that can be embedded in the Track-2 area of a magnetic stripe on a credit card. Such must be reliable and effective, and it must provide years of service life in this embodiment at only a few cents per unit. The prior art has not recognized that maintaining the magnetic data writing currents for more than a very brief period per use will drain the on-board batteries too quickly. New, improved batteries in the future are expected to live longer and have fewer materials issues.
Conventional devices and methods have not appreciated the problems in aligning the data bits from the encoder properly with the statically recorded bits in the rest of the magnetic stripe. Prior art devices do not address the changes in field amplitude matches that can occur with different card swiping speeds. They further have not provided or suggested solutions for the magnetic and mechanical discontinuities that can occur when a thin-film circuit is embedded in a magnetic stripe.